Implement GMM State using osmocom FSM

State machine inspired in the one from TS 24.008 4.1.3.3.1. Some state
transitions are inroduced in the code but are still commented out since
we lack some functionalitites or improvements in the code to handle
different scenarios.

Most of the logic is still outside of the FSM, but at least now the
states are handled in a sane way triggered by events.

Change-Id: Idecb43c10d66224d4f9ba9320825040ce6cf9a07

1 files changed, 187 insertions, 0 deletions

diff --git a/src/sgsn/gprs_gmm_fsm.c b/src/sgsn/gprs_gmm_fsm.c
new file mode 100644
index 000000000..fac06f27e
--- /dev/null
+++ b/src/sgsn/gprs_gmm_fsm.c
@@ -0,0 +1,187 @@
+#include <osmocom/core/tdef.h>
+
+#include <osmocom/sgsn/gprs_gmm_fsm.h>
+
+#include <osmocom/sgsn/debug.h>
+#include <osmocom/sgsn/sgsn.h>
+
+#define X(s) (1 << (s))
+
+static const struct osmo_tdef_state_timeout gmm_fsm_timeouts[32] = {
+	[ST_GMM_DEREGISTERED] = { },
+	[ST_GMM_COMMON_PROC_INIT] = { },
+	[ST_GMM_REGISTERED_NORMAL] = { },
+	[ST_GMM_REGISTERED_SUSPENDED] = { },
+	[ST_GMM_DEREGISTERED_INIT] = { },
+};
+
+#define gmm_fsm_state_chg(fi, NEXT_STATE) \
+	osmo_tdef_fsm_inst_state_chg(fi, NEXT_STATE, gmm_fsm_timeouts, sgsn->cfg.T_defs, -1)
+
+static void st_gmm_deregistered(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch(event) {
+	case E_GMM_COMMON_PROC_INIT_REQ:
+		gmm_fsm_state_chg(fi, ST_GMM_COMMON_PROC_INIT);
+		break;
+	case E_GMM_ATTACH_SUCCESS:
+		gmm_fsm_state_chg(fi, ST_GMM_REGISTERED_NORMAL);
+		break;
+	}
+}
+
+static void st_gmm_common_proc_init(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch(event) {
+	/* TODO: events not used
+	case E_GMM_LOWER_LAYER_FAILED:
+	case E_GMM_COMMON_PROC_FAILED:
+		gmm_fsm_state_chg(fi, ST_GMM_DEREGISTERED);
+		break;
+	*/
+	case E_GMM_COMMON_PROC_SUCCESS:
+	case E_GMM_ATTACH_SUCCESS:
+		gmm_fsm_state_chg(fi, ST_GMM_REGISTERED_NORMAL);
+		break;
+	}
+}
+
+static void st_gmm_registered_normal(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch(event) {
+	case E_GMM_COMMON_PROC_INIT_REQ:
+		gmm_fsm_state_chg(fi, ST_GMM_COMMON_PROC_INIT);
+		break;
+	/* case E_GMM_NET_INIT_DETACH_REQ:
+		gmm_fsm_state_chg(fi, ST_GMM_DEREGISTERED_INIT);
+		break; */
+	/* case E_GMM_MS_INIT_DETACH_REQ:
+		gmm_fsm_state_chg(fi, ST_GMM_DEREGISTERED);
+		break; */
+	case E_GMM_SUSPEND:
+		gmm_fsm_state_chg(fi, ST_GMM_REGISTERED_SUSPENDED);
+		break;
+	}
+}
+
+static void st_gmm_registered_suspended(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch(event) {
+	case E_GMM_RESUME:
+		gmm_fsm_state_chg(fi, ST_GMM_REGISTERED_NORMAL);
+		break;
+	}
+}
+
+static void st_gmm_deregistered_init(struct osmo_fsm_inst *fi, uint32_t event, void *data)
+{
+	switch(event) {
+	/* TODO: events not used in osmo-sgsn code
+	case E_GMM_DETACH_ACCEPTED:
+	case E_GMM_LOWER_LAYER_FAILED:
+		gmm_fsm_state_chg(fi, ST_GMM_DEREGISTERED);
+		break;
+	*/
+	}
+}
+
+static struct osmo_fsm_state gmm_fsm_states[] = {
+	[ST_GMM_DEREGISTERED] = {
+		.in_event_mask =
+			X(E_GMM_COMMON_PROC_INIT_REQ) |
+			X(E_GMM_ATTACH_SUCCESS),
+		.out_state_mask = X(ST_GMM_COMMON_PROC_INIT),
+		.name = "Deregistered",
+		.action = st_gmm_deregistered,
+	},
+	[ST_GMM_COMMON_PROC_INIT] = {
+		.in_event_mask =
+			/* X(E_GMM_LOWER_LAYER_FAILED) | */
+			/* X(E_GMM_COMMON_PROC_FAILED) | */
+			X(E_GMM_COMMON_PROC_SUCCESS) |
+			X(E_GMM_ATTACH_SUCCESS),
+		.out_state_mask =
+			X(ST_GMM_DEREGISTERED) |
+			X(ST_GMM_REGISTERED_NORMAL),
+		.name = "CommonProcedureInitiated",
+		.action = st_gmm_common_proc_init,
+	},
+	[ST_GMM_REGISTERED_NORMAL] = {
+		.in_event_mask =
+			X(E_GMM_COMMON_PROC_INIT_REQ) |
+			/* X(E_GMM_NET_INIT_DETACH_REQ) | */
+			/* X(E_GMM_MS_INIT_DETACH_REQ) | */
+			X(E_GMM_SUSPEND),
+		.out_state_mask =
+			X(ST_GMM_DEREGISTERED) |
+			X(ST_GMM_COMMON_PROC_INIT) |
+			X(ST_GMM_DEREGISTERED_INIT) |
+			X(ST_GMM_REGISTERED_SUSPENDED),
+		.name = "Registered.NORMAL",
+		.action = st_gmm_registered_normal,
+	},
+	[ST_GMM_REGISTERED_SUSPENDED] = {
+		.in_event_mask = X(E_GMM_RESUME),
+		.out_state_mask =
+			X(ST_GMM_DEREGISTERED) |
+			X(ST_GMM_REGISTERED_NORMAL),
+		.name = "Registered.SUSPENDED",
+		.action = st_gmm_registered_suspended,
+	},
+	[ST_GMM_DEREGISTERED_INIT] = {
+		.in_event_mask = 0
+			/* X(E_GMM_DETACH_ACCEPTED) | */
+			/* X(E_GMM_LOWER_LAYER_FAILED) */,
+		.out_state_mask = X(ST_GMM_DEREGISTERED),
+		.name = "DeregisteredInitiated",
+		.action = st_gmm_deregistered_init,
+	},
+};
+
+const struct value_string gmm_fsm_event_names[] = {
+	OSMO_VALUE_STRING(E_GMM_COMMON_PROC_INIT_REQ),
+	/* OSMO_VALUE_STRING(E_GMM_COMMON_PROC_FAILED), */
+	/*  OSMO_VALUE_STRING(E_GMM_LOWER_LAYER_FAILED),  */
+	OSMO_VALUE_STRING(E_GMM_COMMON_PROC_SUCCESS),
+	OSMO_VALUE_STRING(E_GMM_ATTACH_SUCCESS),
+	/*  OSMO_VALUE_STRING(E_GMM_NET_INIT_DETACH_REQ), */
+	/*  OSMO_VALUE_STRING(E_GMM_MS_INIT_DETACH_REQ), */
+	/* OSMO_VALUE_STRING(E_GMM_DETACH_ACCEPTED), */
+	OSMO_VALUE_STRING(E_GMM_SUSPEND),
+	OSMO_VALUE_STRING(E_GMM_CLEANUP),
+	{ 0, NULL }
+};
+
+void gmm_fsm_allstate_action(struct osmo_fsm_inst *fi, uint32_t event, void *data) {
+	switch (event) {
+	case E_GMM_CLEANUP:
+		switch (fi->state) {
+		case ST_GMM_DEREGISTERED:
+			break;
+		default:
+			gmm_fsm_state_chg(fi, ST_GMM_DEREGISTERED);
+			break;
+		}
+	}
+}
+
+int gmm_fsm_timer_cb(struct osmo_fsm_inst *fi)
+{
+	return 0;
+}
+
+struct osmo_fsm gmm_fsm = {
+	.name = "GMM",
+	.states = gmm_fsm_states,
+	.num_states = ARRAY_SIZE(gmm_fsm_states),
+	.event_names = gmm_fsm_event_names,
+	.allstate_event_mask = X(E_GMM_CLEANUP),
+	.allstate_action = gmm_fsm_allstate_action,
+	.log_subsys = DMM,
+	.timer_cb = gmm_fsm_timer_cb,
+};
+
+static __attribute__((constructor)) void gmm_fsm_init(void)
+{
+	osmo_fsm_register(&gmm_fsm);
+}